Method for forming a composite comprising MFC and a composite produced by the method

The invention provides a method for the production of a composite comprising microfibrillated cellulose (MFC) and precipitated calcium carbonate. The method is characterized in that MFC is added to a suspension of calcium hydroxide during carbonation， whereby calcium carbonate is precipitated onto fibers or fibrils of the MFC in a controlled manner. By adding microfibrillated cellulose to the calcium suspension during the carbonation， the brightness and the strength of the MFC/PCC-composite is enhanced. Moreover， the inventive method facilitates the distribution of calcium dioxide and MFC in the suspension and thus gives rise to a more homogenous product.